Alkyl-O-cleavage

Oxaziridines substituted in the 2-position with primary or secondary alkyl groups undergo decomposition at room temperature. In the course of some weeks, slow decomposition of undiluted compounds occurs, the pattern of which is analogous to that of acidic or alkaline N—O cleavage (Sections 5.08.3.1.3 and 4), Radical attack on a C—H bond in (109) effects N—O cleavage, probably synchronously (57JA5739). In the example presented here, methyl isobutyl ketone and ammonia were isolated after two hour s heating at 150 °C. 

In the special case of nucleophilic substitution at a sulfonic ester RS020R where R is alkyl, R —O cleavage is much more likely than S—O cleavage because the OSOiR group is such a good leaving group (p. 353).1730 Many of these reactions have been considered previously (e.g., 0-4, 0-14, etc.), because they are nucleophilic substitutions at an alkyl carbon atom and not at a sulfur atom. However, when R is aryl, then the S—O bond is much more likely to cleave because of the very low tendency aryl substrates have for nucleophilic substitution.1731... 

Aliphatic amines undergo a characteristic o cleavage in the mass treuneter. similar to that Observed far alcohols, A C-C l d nearest the nil gen atom is broken, yielding an alkyl radical and a nitro n Cptttaii... 

Hydrolysis of alkyl-substituted phosphine oxides is generally difficult, heating with solid sodium or potassium hydroxide is needed in order to break the P—C bond. Hydrolysis of phosphonates and phos-phinates occurs with P—O cleavage in preference to P—C cleavage. Exceptions have been reported with several aromatic phosphine oxides containing p- and o-nitrobenzyl groups and other stabilized systems. Perfluorinated phosphine oxides can also be hydrolyzed to the phosphinic and phosphonic acids.2 ... 

Sulfonyl chlorides as well as esters and amides of sulfonic acids can be hydrolyzed to the corresponding acids. Sulfonyl chlorides can by hydrolyzed with water or with an alcohol in the absence of acid or base. Basic catalysis is also used, though of course the salt is the product obtained. Esters are readily hydrolyzed, many with water or dilute alkali. This is the same reaction as 10-4, and usually involves R —O cleavage, except when R is aryl. However, in some cases retention of configuration has been shown at alkyl R, indicating S—O cleavage in these cases. Sulfonamides are generally not hydrolyzed by alkaline treatment, not even with hot concentrated alkali. Acids, however, do hydrolyze sulfonamides, but less readily than they do sulfonyl halides or sulfonic esters. Of course, ammonia or the amine appears as the salt. However, sulfonamides can be hydrolyzed with base if the solvent is HMPA. ... 

Since aryl-0 bond energy is in the order of 90 kcal/mol and greater than the alkyl-O bond energy ( 80 kcal/mol), the first site expected to be cleaved in aryl alkyl ethers is the alkyl-oxygen bond. A recent paper by Milstein et al. reports that the point of cleavage can be directed by using different metal complexes (Eq.34) [81]. 

The reactions with alkyl-substituted alkenes proceed to give the cycloadducts in good yields. Presumably, the cyclic cationic compound is formed as an initial product, which then undergoes the Me-O cleavage reaction upon treatment with triethylamine during the work-up to give the neutral compound as the final product (Scheme 8.11). 

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